<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>验证码</title>
</head>

<body>
  <span id='span'></span>
  <script>
    !(function (window, document) {
      function GVerify(options) { //创建一个图形验证码对象，接收options对象为参数
        this.options = { //默认options参数值
          id: "", //容器Id
          canvasId: "verifyCanvas", //canvas的ID
          width: "500", //默认canvas宽度
          height: "500", //默认canvas高度
          type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
          code: ""
        }

        if (Object.prototype.toString.call(options) == "[object Object]") {//判断传入参数类型
          for (var i in options) { //根据传入的参数，修改默认参数值
            this.options[i] = options[i];
          }
        } else {
          this.options.id = options;
        }

        this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(",");
        this.options.letterArr = getAllLetter();

        this._init();
        this.refresh();
      }

      GVerify.prototype = {
        /**版本号**/
        version: '1.0.0',

        /**初始化方法**/
        _init: function () {
          var con = document.getElementById(this.options.id);
          var canvas = document.createElement("canvas");
          this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100";
          this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30";
          canvas.id = this.options.canvasId;
          canvas.width = this.options.width;
          canvas.height = this.options.height;
          canvas.style.cursor = "pointer";
          canvas.innerHTML = "您的浏览器版本不支持canvas";
          con.appendChild(canvas);
          var parent = this;
          canvas.onclick = function () {
            parent.refresh();
          }
        },

        /**生成验证码**/
        refresh: function () {
          this.options.code = "";
          var canvas = document.getElementById(this.options.canvasId);
          if (canvas.getContext) {
            var ctx = canvas.getContext('2d');
          } else {
            return;
          }

          ctx.textBaseline = "middle";

          ctx.fillStyle = randomColor(180, 240);
          ctx.fillRect(0, 0, this.options.width, this.options.height);

          if (this.options.type == "blend") { //判断验证码类型
            var txtArr = this.options.numArr.concat(this.options.letterArr);
          } else if (this.options.type == "number") {
            var txtArr = this.options.numArr;
          } else {
            var txtArr = this.options.letterArr;
          }

          for (var i = 1; i <= 4; i++) {
            var txt = txtArr[randomNum(0, txtArr.length)];
            this.options.code += txt;
            ctx.font = randomNum(this.options.height / 2, this.options.height) + 'px SimHei'; //随机生成字体大小
            ctx.fillStyle = randomColor(50, 160); //随机生成字体颜色        
            ctx.shadowOffsetX = randomNum(-3, 3); // 设置或返回阴影距形状的水平距离
            ctx.shadowOffsetY = randomNum(-3, 3); // 设置或返回阴影距形状的垂直距离
            ctx.shadowBlur = randomNum(-3, 3); // 设置或返回用于阴影的模糊级别
            ctx.shadowColor = "rgba(0, 0, 0, 0.3)"; // 设置或返回用于阴影的颜色
            var x = this.options.width / 5 * i;
            var y = this.options.height / 2;
            var deg = randomNum(-30, 30);
            /**设置旋转角度和坐标原点**/
            ctx.translate(x, y);
            ctx.rotate(deg * Math.PI / 180);
            ctx.fillText(txt, 0, 0);
            /**恢复旋转角度和坐标原点**/
            ctx.rotate(-deg * Math.PI / 180);
            ctx.translate(-x, -y);
          }
          /**绘制干扰线**/
          for (var i = 0; i < 4; i++) {
            ctx.strokeStyle = randomColor(40, 180);
            ctx.beginPath();
            ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height));
            ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height));
            ctx.stroke();
          }
          /**绘制干扰点**/
          for (var i = 0; i < this.options.width / 4; i++) {
            ctx.fillStyle = randomColor(0, 255);
            ctx.beginPath();
            ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);
            ctx.fill();
          }
        },

        /**验证验证码**/
        validate: function (code) {
          var code = code.toLowerCase();
          var v_code = this.options.code.toLowerCase();
          console.log(v_code);
          if (code == v_code) {
            return true;
          } else {
            this.refresh();
            return false;
          }
        }
      }
      /**生成字母数组**/
      function getAllLetter() {
        var letterStr = "a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
        return letterStr.split(",");
      }
      /**生成一个随机数**/
      function randomNum(min, max) {
        return Math.floor(Math.random() * (max - min) + min);
      }
      /**生成一个随机色**/
      function randomColor(min, max) {
        var r = randomNum(min, max);
        var g = randomNum(min, max);
        var b = randomNum(min, max);
        return "rgb(" + r + "," + g + "," + b + ")";
      }
      window.GVerify = GVerify;
    })(window, document);
    let gverify = new GVerify({
      id: "span", //容器Id
      canvasId: "verifyCanvas", //canvas的ID
      width: "500", //默认canvas宽度
      height: "300", //默认canvas高度
      type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
      code: ""
    });
  </script>

</body>

</html>